SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3effeedfe58e6ab7b91755c033a8df37bc9c728ca86b1de25563b341ab36c920' 
  AND token = 'RzZzA7rt3plYqCTTUZGrUNoE/hcGVGstYoQUTURq/wQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}